Corresponding Author

Competing Interests

The authors have the following competing interest: E. Kissling, M. Valenciano, T. Seyler, C. Savulescu and A. Moren are employees of EpiConcept, Paris. J.M. Cohen and I. Daviaud are employees of GROG/Open Rome, Paris. As Head of Open Rome, J.M. Cohen is involved in several epidemiological studies that are partially or fully funded by pharmaceutical companies (Sanofi-Pasteur, GSK, Roche), nonprofit organizations (Mutuelles, Résaeu DES France) or public institutions (ECDC, CU Strasbourg). He is a member of Association Mieux Prescrire and the advisory boards of Novartis, Roche, and Wyeth (free participation, no compensation). During the past five years, he has received travel grants from Sanofi-Pasteur and Roche. I. Daviaud is involved, through the other institution with which she is affiliated and salaried (Open Rome research department), in the coordination or analysis of epidemiological studies partially or fully funded by Roche and GSK. EpiConcept conducted for the Mexican Social Security and GSK an evaluation of the Mexican hospital based surveillance system for intussusceptions (2008). EpiConcept coordinated studies for measuring influenza vaccine effectiveness funded by EVM, the association of the European Vaccine Manufacturers. None of the current authors were involved in these studies (2009). EpiConcept conducts for SP-MSD the data analysis of a study conducted in Finland to measure the impact of rotavirus vaccination on hospitalisation for acute gastroenteritis due to rotavirus infection (2009-10). There are no patents, products in development or marketed products to declare. This does not alter the authors' adherence to all the PLoS ONE policies on sharing data and materials. All other authors have declared that no competing interests exist.